aviation vhf handheld radio problem

[pwm]

I bought a Vertex VXA-210 vhf aviation handheld and am experiencing a
strange tone when attempting to transmit with my David Clark headset plugged
into it. The tone is not present if I disconnect the mic plug from the
headset adapter. The tone also fades away if I remove the "rubber ducky"
antenna or if I cover the mid-section of the antenna with my hand while
transmitting. The radio has a feature to turn off its built-in mic with the
headset connected and I have selected it to "off", but find it odd that when
the headset mic plug is disconnected and transmit, I can tap on the radio's
mic and faintly hear the tapping sound in my headset...

Any ideas?

Thanks,
Monty

[[email protected]]

The 210 manual doesn't say it but the later models say not to use the
monitor function with an external mic or you can get feedback.
Ray

On Sun, 5 Feb 2006 10:39:32 -0600, "pwm" > wrote:

>I bought a Vertex VXA-210 vhf aviation handheld and am experiencing a
>strange tone when attempting to transmit with my David Clark headset plugged
>into it. The tone is not present if I disconnect the mic plug from the
>headset adapter. The tone also fades away if I remove the "rubber ducky"
>antenna or if I cover the mid-section of the antenna with my hand while
>transmitting. The radio has a feature to turn off its built-in mic with the
>headset connected and I have selected it to "off", but find it odd that when
>the headset mic plug is disconnected and transmit, I can tap on the radio's
>mic and faintly hear the tapping sound in my headset...
>
>Any ideas?
>
>Thanks,
>Monty

[News]

pwm wrote:
> I bought a Vertex VXA-210 vhf aviation handheld and am experiencing a
> strange tone when attempting to transmit with my David Clark headset
> plugged into it. The tone is not present if I disconnect the mic plug
> from the headset adapter. The tone also fades away if I remove the
> "rubber ducky" antenna or if I cover the mid-section of the antenna with
> my hand while transmitting. The radio has a feature to turn off its
> built-in mic with the headset connected and I have selected it to "off",
> but find it odd that when the headset mic plug is disconnected and
> transmit, I can tap on the radio's mic and faintly hear the tapping
> sound in my headset...
>
> Any ideas?
>
> Thanks,
> Monty
>
Its RF feedback coming straight back into the headset lines.... Its
happens on mine but when i plug another aerial into the top it goes
away. You just cant use the rubber ducky aerial and headsets at the same
time you must use an external aerial. Thanks

[COLIN LAMB]

You should be able to eliminate th rf feedback with the use of a ferrite
material around the headset cable.

Look at http://audiosystemsgroup.com/SAC0305Ferrites.pdf for some technical
information on the subject.

Colin